1. Field of the Invention
The present invention relates to an optical member such as a lens element preferably applicable to optical communication devices, tools, and systems and more particularly, to an optical member such as a micro-lens suitable for constituting things by means of a microscopic optical element of the diffraction type such as a Computer Generated Holographic (CGH) optical element. The invention also relates to a method for manufacturing the optical member as described above, an optical module, and a method for mounting the optical member as mentioned above.
2. Prior Art
With regard to the optical member coupled to a laser diode and an optical fiber in the field of the optical communication, Japanese patent publication No. 7-199006 and No. 11-295561 have already disclosed it publicly. The former proposes an optical coupling by means of a ball lens in the form of a sphere while the latter describes a circular lens provided with an annular portion formed along the external edge of the lens.
There has also been devised and reported an optical member like a lens which is manufactured by using a photo-lithography and etching technique and used in the above field. In this example, a lens or the like having a desired shape is formed on the silicon substrate by using the photolithographic process.
Being formed in this way, the lenses are often treated in the thin film formation process to be coated with a tin film, an anti-reflection film, a filtration film and so forth, for instance.
These lenses are arranged and mounted in their respective predetermined positions on a semiconductor substrate, on which a laser diode, an optical fiber, and other elements are mounted, such that the respective optical axes of them meets those of corresponding elements. At the time of mounting, these lenses are arranged on corresponding grooves formed on the semiconductor substrate, thereby being appropriately positioned to be coupled to the laser diode, the optical fiber and other corresponding elements.